1. Field of Invention
This invention relates to ice skates, more specifically to the juxtaposition of toe-picks and skating surfaces incorporated into figure skates, and to sharpening enhancement.
2. Prior Art
The most pertinent prior art is the applicant's own research through the years 1988-92 for the Sports Equipment and Technology Committee (SETC) of the US Olympic Committee (USOC) in that time period. This has been covered by two technical reports published or available from that organization, citations A & B, the applicant's privately published Skateology Manual, citation C and a skating trade newspaper, citation D, as given on the accompanying Information Disclosure Statement. The intent of this sub-committee of the USOC was to aid the sports equipment manufacturers in many different sports including Figure Skating with outside engineering and scientific specialists.
Before the prior art ramifications of these documents can be reviewed, basic characteristics of skate technology require, terminology, definition or explanation including a blade characteristic vital to the technical presentation and comprehension of this application, namely: the ‘Non Skateable Zone’ (NSZ). For the latter, a single sheet document, citation E, is referenced as the most precise instrument for doing this. At the same time it introduces a unique gage for use by skate sharpeners, skating coaches and skaters for assessing the performance degradation caused by the sharpenings that blades regularly require. It does this by measuring the concomitant lengthening of this NSZ with indexes defining levels of degradation. This feature constitutes an unique paradigm for technical explanation in this application. Citation E, identifying this gage as the Blade Wellness Gage (BWG), will be referred to as the ‘BWG info. sheet’. It is to be noted that in the two USOC reports, the applicant used the term Un-Skateable Zone (USZ) however the more recent usage of NSZ as disseminated in the applicant's Skateology Manual, page VII:14, will be used in the following text.
Almost all Figure skate structures have a permanently incorporated blade component that extends at least the full length of the foot having a lower peripheral surface to engage the ice in customary manner. Mounting provisions allow for attachment to a skating boot. A low cost version incorporates the blade into a molded extension of the boot structure. Others incorporate the blade either permanently or replaceable in an aluminum structure similar to a hockey skate but regardless of structure all figure skates have integral toe-picks at the front embodying several teeth. The design illustrated on page 23 of referenced Skateology Manual with brazed on sole and heel plates will be referred to as traditional.
The peripheral surface, in future termed the skating-surface, is rocketed meaning that it is provided with a longitudinally convex profile, termed the rocker that limits the extent of engagement between blade and the ice surface to a small lengthwise segment of the blade profile. This facilitates the classic maneuverability typical of figure skating. Regardless of the differences in skate structure as mentioned above, a ubiquitous feature is the frontal toe-pick with its protruding lowest tooth from which the rockered skating surface extends rearward. Such a lower tooth is termed a drag tooth, a definition to be applied throughout this specification and claims.
The rocker profile crests at approximately mid-length of the blade but the location of the balance point along the length of the blade will vary according to the skating mode being employed and the particular stance that the skater wishes to adopt during that skating mode. The exact curvature of this profile is extremely important to skating performance and the skate manufacturer uses precision profiling methods to ensure accuracy of their product as it leaves the factory. This ‘new’ profile is considered ideal in facilitation a figure skate's performance including numerous types of jumps, spins and artistry all depending on the profile being maintained as accurately as possible. The more important forward portion of the profile is a non-circular arc with the remainder of the length nominally circular.
Another geometrical feature equally essential to the mechanism of skating is the provision of sharp corners along the entire length of this rockered skating-surface. These have acquired the term ‘edges’. The keenness of these edges is very critical and inevitable become blunted with use, attributed to the abrasive effect of a solid particle content in the ice. Consequently, re-sharpening becomes necessary from time to time and since the blade is manufactured from hardened steel a grinding operation is resorted to. Additionally, to enhance sharpness of these edges as measured by the ‘bite angle’ term explained on page l:1 and l:4 of referenced Skateology Manual, a longitudinal groove of circular cross section is provided in the skating surface. This involves removing metal from the entire width of the skating surface merely to establish a preferred sharpness and essential keenness at the extreme edge. The useful life of a blade is therefore contingent upon the amount of blade that can be removed by sharpening without significantly affecting its functional capability. The necessary blade hardness for satisfactory edge sharpness and keenness will never be a factor in this consideration since any quality blade, regardless of manufacturer, will have adequate hardness depth. It is the incremental change of rocker profile, a progressive flattening with each sharpening degrading blade performance, that is the usual blade life-determining feature. A more climactic reason and quite frequent is when flattening degenerates into concaving in the NSZ. This is shown, to scale, in an actual high level skater's blade in the referenced information sheet introducing the applicant's Blade Wellness Gauge, henceforth referred to as the BWG info sheet. The reason for this is twofold:    1. Virtually all sharpening of figure blades is accomplished using grinding wheels rotating in the plane of the blade, the primary reason being that it is a simple operation to profile the periphery of the wheel to the required radius of the groove needed in the skating surface of the blade. This groove is a variable dependent on the weight of the skater, the thickness of the blade and the temperature/hardness of the ice about to be skated on. Additionally this mode of grinding provides a superior surface finish that in turn improves the quality of the skating edge, enhancing flow of the blade on the ice and control of skating maneuvers. Unfortunately, in conjunction with reason 2 below, the wheel can only commence or finish its cut some distance rearward of the drag tooth leaving the very frontal portion of the rocker profile unsharpened, see FIG. 24.    2. The lowest tooth of the toe-pick, termed the drag tooth is the culprit preventing access of the grinding wheel to the frontal portion of the rocker profile; specifically its protrusion from the rocker profile, see FIG. 24. It also adds difficulty to the sharpening process: sharpeners normally start their sharpening pass at the front of the blade as close as practical to the drag tooth are obliged to adopt a tricky ‘touch and go’ routine. Depending on the ease of traversing of the skate carriage on any particular sharpening machine, this leads to a nudging in of the blade on to the wheel often too forcefully actually corrupting the blade's profile, starting with a localized concavity that progressively envelopes the forward part of the blade. This prematurely wrecks the blade for serious skating.
While the above reasons are the causes of the limited life expectancy of a figure blade, a parameter previously identified, the “Non-Skateable-Zone” (NSZ), is becoming the measure of blade life expectancy for the serious minded technicians, skaters and coaches in the sport. It is a measure of that portion of the blade immediately rearward of the toe-pick that cannot be skated on, skating being understood as the gliding of the skater normally with one edge only of the blade engaging the ice on an arcuate path. This is because the skater, to achieve equilibrium, must ‘lean-into-the-circle’ to counterbalance centrifugal force. The zone is nevertheless critical to jumping and spinning.
The extent of the NSZ is defined as the length from the drag tooth's tip to where a straight edge, when placed against that tip and against the rocker profile becomes tangent to that profile as shown in FIG. 1 of the BWG info sheet. The rearward limit of this zone coincides with the skater's balance point on the rocker profile when the tip of the drag tooth is aligning with the ice. It encompasses the combined surfaces of the drag tooth and the skating surface subtending a prescribed NSZ length. FIG. 2 of the BWG info sheet demonstrates how prior art has led to the type of sharpenings that can devastate a skater's performance and wreck a competitive skater's career: Another reason for introducing this reference is that it amplifies a further critical shortcoming of prior art, the very limited life of a figure skate as compared to the toe-pick less hockey blade. The Blade Wellness Gauge illustrated puts the concept of the NSZ to practical use in assessing this limited lifespan during which the critical rocker contour within the lengthening NSZ is being degraded. The gage measure this lengthening with index marks indicating the life expectancy of the blade appropriately color coded green and red respectively. Its usage here verifies the seriousness this application addresses.
Reference is now made to the two indexes labeled “NEW” and “DEGRADING”. The span between these two indexes, printed in green on the actual gauge, is indicative of an acceptable life span. For the NSZ to increase from the one to the other involves an average of 0.9 mm metal removal from the blade's rocker profile as a result of sharpenings. This is designated: the serviceable or viable limit of the life of a blade for a competent skater. The resulting change of geometry is illustrated in FIG. 24 of the application assuming a careful sharpener has maintained a convex profile albeit significantly flatter than the original and leaving a slight hump immediately behind the drag tooth. A less skilled and less knowledgeable sharpener may have in all likelihood commenced the concavity depicted in FIG. 2 of the BWG Info sheet. The extent of blade degradation illustrated, for any level of skating, is is appalling. All this is due to the difficulty of commencing a grinding pass with the drag tooth obstructing a free approach path of the blade relative to the grinding wheel when starting a sharpening pass. Means for avoiding this is long overdue.
The primary purpose of the toe-pick is to facilitate jumping, both on take-off into the jump and upon landing. It comprises several teeth usually aligned at an angle approximately 50° to a plane through the mounting surfaces of the skate and extends from the center front of the blade to the rockered skating surface, with the lowest tooth protruding, as preciously observed, somewhat proud of the rocker profile. In some blade designs an adjacent tooth may also protrude proud of a virtual projection of the rocker profile. It is the problems caused by fabricating these protruding teeth, usually together with the other teeth of the toe-pick, integrally with the blade, that this invention, in addition to other advantages, is designed to overcome. Basically, these integral teeth make it impossible to replicate the original, ideal, new rocker profile of the blade during sharpening, as previously described. The drag tooth is so termed because it also serves to stabilize a single foot spin known as a scratch spin.
The rocker profile in this NSZ and its length is the most critical portion of the blade becoming functional during the initial takeoff and landings of most kinds of jumps when the drag tooth together with some portion of the NSZ momentarily penetrates below the ice surface. During this brief but critical period the NSZ portion of the blade provides control. Skaters are consequently extremely sensitive to blade profile, edge keenness and the sharpness in this zone. The limits as determined by the applicant, on the allowable growth of the NSZ and concomitant loss of performance acceptable to the experienced skater are tabulated below. These values are taken from the BWG info. sheet, Citation E. For the recreational skater considerably different matrix would pertain. Such matrix of values or alternative as deriving from some other source is implicit whenever the term NSZ is used in this application. It determines acceptable extents of metal removal from the skating surface, a basic factor in this application. While emphasizing the deplorable condition of prior art it comprises an essential explanatory tool for use in this application. In regard to the dimensional aptness of the NSZ lengths used to locate the four indexes they result from the applicants 30 years of experience designing sharpening machines specifically for figure skates, research for the USOC examining elite
Blade sizeBlade SizeBlade SizeBlade SizeRangeRangeRangerangeNSZ Condition7¼″-8″8¼″-9″9¼″-10″10¼″-11″New1.4″1.5″1.6″1.9″Degrade Limit1.8″1.9″2.1″2.4″The term blade in this chart has to be interpreted as skate for the technical level of this specificationskater's blades using the test data sheets of page 23 of citation A and some 60 years of actual skating experience. They are a pioneering analytical substitute for experimental verification that the aborted testing by elite skaters, using the applicant's adjustable height, attachable detachable toe-pick equipped skates would have provided. These constitute part of prior art and will be appropriately reviewed.
Furthermore, while the main problem resulting from the lengthening of the NSZ, as sharpenings proceed, is the reduced efficiency of the blade for both jumping and spinning, the powering ability of the skater is also diminishing, there being less blade length available from which to power. Powering, the means of replenishing momentum, is termed stroking in the figure skating world. During stroking the blade's edge/ice engagement location progresses along the length of the blade from the rear of the blade forward, terminating as far forward as possible without allowing the drag tooth to engage the ice. Stroking is always from an edge and a lengthened NSZ deprives the skater of some forward, more effective portion of the blade, the drag tooth tending to drag the ice much sooner during the stroking action. Unlike in normal skating, as explained earlier, part of the edge within the NSZ becomes accessible for powering due to the low angle of the blade to the ice during stroking. Allowing the toe-pick to engage the ice is termed toe-picking and considered poor, inefficient technique. It is emphasized that all the above problems and shortcomings result from the inability to freely sharpen the full length of a figure blade—due to an obstructing drag tooth. This application is concerned with means for rectifying this situation.